Dynamic properties of the photoreceptor membranes from bovine rod outer segment are investigated with quasielastic light scattering. The membranes are isolated in vesicular forms and suspended in well defined media such as aqueous Ficoll solution (5% by weight) or sucrose solution (4 x 10 to the minus 3rd power by weight), and their vesicular dimension, surface undulation dynamics and rotatory diffusion behaviors of photopigments are examined by the spectral profiles of scattered light from a He/Ne laser source. Two configurations of quasielastic scattering are employed; one is the angular dependent polarized scattering for the translational diffusion and the other is the forward depolarized scattering for the internal normal modes. In addition, the elastic scattering profile with respect to the scattering angle is acquired in order to determine the shapes of the membrane vesicles in different media with varying osmolalities. The focus is set on the photoinduced calcium ion gating from the intravesicular fluid to the extravesicular space and on the mechanism of the gating vis-a-vis the photochemical processes within the photopigments. BIBLIOGRAPHIC REFERENCE: S.A. Shaya & H. Yu, Order Fluctuation Dynamics of Nematic Liquid Crystal in a Binary System: MBBA/Biphenyl, J. Chem. Phys. (1975) 63, 221-227.